Hydrocarbons such as oil and natural gas are typically extracted from the earth via drilled wells. In a typical well drilling operation, a drill bit is attached to joined sections of drill pipe, positioned within a wellbore and set into rotational motion. As the drill bit rotates, it removes material from the bottom of the wellbore. A fluid referred to as “drilling mud” or simply “mud” is pumped through the drill pipe to remove the cut material from the drill bit and the wellbore. The drilling mud flows down the drill pipe, passes through the drill bit, and flows back up the wellbore around the drill pipe to the surface.
Large reciprocating pumps called “slush pumps” or “mud pumps” are typically used for pumping the drilling mud. Mud pumps must deliver drilling mud at relatively high flow rates in order to be effective. Because the drilling mud must also be pumped through thousands of feet of drill pipe, mud pumps typically operate at very high pressures.
Mud pumps are typically of modular construction and include a power end and a fluid end. The power end provides the power for the pump, typically from an internal combustion engine or an electric motor. The power end typically converts rotation motion of an engine or motor to reciprocating motion of an output shaft called an “extension rod.” The designs of large reciprocating pumps have evolved over time, as indicated in U.S. patents numbered U.S. Pat. Nos. 5,616,009; 5,904,071; and 7,168,361, each of which is incorporated herein by reference in its entirety.
The fluid end of a mud pump typically includes components that interact with the drilling mud, such as pistons, cylinder liners, and valves. Drilling mud is often highly abrasive because even after filtering, it contains cut material from the bottom of the wellbore. As a result, moving parts of the fluid end that contact the drilling mud tend to wear relatively quickly, and are normally designed to be replaceable. The moving parts of the fluid end are often replaced at set intervals as part of a regular maintenance schedule, some as often as every few weeks.
The fluid end typically includes one or more pistons, each connected to one end of a piston rod. The other end of each piston rod is typically adapted for connection to an end of an extension rod from the power end. As described above, worn pistons and cylinder liners are typically replaced on a regular basis. To reduce mud pump down time, it is desirable that the replacement of worn pistons and cylinder liners be accomplished as quickly as possible.
In a typical mud pump, a removable connector assembly is used to connect an end of each piston rod to an end of a corresponding extension rod. During the frequent replacement of worn pistons and cylinder liners, the connector assemblies are first removed (to disconnect the ends of the piston rods from the ends of the extension rods), then reinstalled (to reconnect the ends of the piston rods to the ends of the extension rods). From time to time, when the connector assemblies are removed, they are found to be damaged (usually due to an incorrect last reinstallation) and must be replaced.
The ends of extension rods and piston rods of different models of mud pumps tend to have different configurations. As a connector assembly must mate properly with the ends of the extension rod and the piston rod, each mud pump model tends to require a different connector assembly. A problem arises in that a mud pump user having several different models of mud pumps must keep a sufficient number of the different connector assemblies on hand.